SH7708 datasheet(239/633 Pages) RENESAS

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Bit:

Bit name:

—

Initial value:

R/W:

Bit:

Bit name:

Initial value:

R/W:

R/W

10.2.11

Refresh Time Constant Register (RTCOR)

The refresh time constant register (RTCOR) is a 16-bit read/write register. The values of RTCOR

and RTCNT (lower 8 bits) are constantly compared. When the values match, the compare match

flag (CMF) in RTCSR is set and RTCNT is cleared to 0. When the refresh bit (RFSH) in the

individual memory control register (MCR) is set to 1 and the refresh mode is set to CAS-before-

RAS refresh, a memory refresh cycle occurs when the CMF bit is set. RTCOR is initialized to

H'00 by a power-on reset. It is not initialized by a manual reset or in standby mode, but retains its

contents.

Note:

The method for writing to RTCOR is different from that for general registers to prevent

inadvertent overwriting. Using a word transfer instruction, place B'10100101 in the upper

byte and the write data in the lower byte. For details, see section 10.2.13, Cautions on

Accessing Refresh Control Related Registers.

Bit:

Bit name:

—

Initial value:

R/W:

Bit:

Bit name:

Initial value:

R/W:

R/W

10.2.12

Refresh Count Register (RFCR)

The refresh count register (RFCR) is a 16-bit read/write register containing a 10-bit counter that

increments every time RTCOR and RTCNT match. When RFCR exceeds the count limit value set

SH7708 Datasheet(PDF) 239 Page - Renesas Technology Corp